Flashlight lamp



Mardl 30, 1943. .1. A.. M. VAN LIEMPT' FLASH-LIGHT LAMP Filed April 8, 1941 INVENTOR. JAM l/AA/A/E/VPT lPatenieri Mar. 3%,, 1%43 H FLASGHT LAW iohannes Antonius Maria van Liempt, Eindhoven',Nethei-lands; vested in the Alien Property (lust odian fl i V Application April 8,1941, Serial No. 381507 a v In the Netherlands April 11, 1940 v vt Claims. (01.67-31) g It was found a longtime ago that a flash-light light-output in proportionto the quantity added.

lamp should have a flash-time which is not ex- These twoinjurious efiects practically start to cessively short. Such for two reasons: occur beyond 30% of N20.

, The two injurious eflz'ects of the N20 addition When makinginstantaneous exposures there is r greater probability that the synchronize'r oper t favoumlfflei by itbelf m be ating the shutter 01 the camera will cause the balanced by W use of qulcke-r actmg shutter toopen during that part of the exg g agam g i incrgase of the r 1 pressure 0 e gas or e vo ume of he bulb. posu e t me Characteristic curve of the flash Satisfactory mixtures are those containing from 1g t amp n which the light emissmn is a 10V 10 to 60% by volume of N20 gas, more particumaximumythis is or particular-importance in i v connection with iris shutters; L gggf: containmg fmm b0 50% by gg g igggi fg sgggg pi ggz 28:: For constituting the combustible material. use respondingly long fleh-tlmes to ensure that the EZy 1 2 fig gi gg ggs gi gfii negative be entire exposed. Efforts have therefore been made to make flash-light lamps 3 1 335: g gggfi fig ggg g g' g with longer flash-time by using comparatively stances ys ese gg gg z g igi g gg a a; 32 32:? To explain the invention we may mention that time characteristic curve but the defect of this the additions of other gases such as N: and CO: lamp is that the time lag 1 e the time which also result in lengthening of the flash-time but elapses between establishmn of the ignmbn these additions have such a cooling effect during current and the commencement of light develcombustion that the ught'output Humans per opment is far too long I mgr. of combustible material) is reduced to such v an extent and the ignition may in addition occur This defect may be avoided by manufacturin so late and s0 irregularly that these disadvanlamps which are not provided with a, simple filltages cannot be simply balanced. ing but with combustible material constituted by In order that the invention may be clearly mixtures of thin and hick mini m f il, n understood and readily carried into efiect I shall and thick alumlnium wire or h and thick r describe .the same in more detail with reference of an aluminium alloy of for e ample aluminium to the accompanying drawing in which the single with 7% oi'ma n lum, in which cases a normal figure is a side view of a flash lamp'according time lag is obtained. to the invention.

Efforts have also been made to pr l the The flash lamp shown in the drawing comprises .ilash-tlme by eccentric arran m n 01 h i a bulb for transparent material having a. base tion filament or a in by the arrangement f a 2, combustible material 3 in the form of thinwire, I screen in the bulb with the result that the comd an igniter 5 hich serves to ignite the ma- Q bustion path is artificially lengthened, by the use t 1 3, The mt 5 comprises filam nt s s of tubular bulbs and so for h supported by two wires 1 and carrying an lgni All thes c n r i er, have the dis- 40 tion mixture 4 consisting, for example, of a puladvanta e of be n complicated. verized metal, for instance aluminum, an oxi- According to the present invention, the object dizing agent, for instance lead dioxide, and a. aimed at is reached by quite difierent means viz binder, for instance nitrocellulose or siliceous by a suitable choice of the nature ofthe gasvarnish. In accordance with the invention the filling. 4 bulb is filled with a mixture 8 of oxygen and According to the invention, the gas filling is N20, the quantity of N20 being fr0m 10% to 60%, constituted by oxygen having added to it'from 10 preferably 20% to by volume of the mixto by volume of N20 gas. The proportion ture. Y l used depends on the desired flash-time whereby The advantages of the invention will be shown the greater the quantity added the longer is the 50 by the following comparison between alamp havi'lash-time. ing a filling of oxygen and a lamp which is the The N20 addition, however, also has the effect same as the first lamp except that, in accordance of increasing the above-described time lag in 'with the invention, it contains a mixture of proportion to the quantity of N20 added. The oxygen and N20.

N20 addition also has the effect of lowering the 5 An incandescent lamp bulb having a diameterof 55 mms., is filled with 27 mgr. of alloy wire having a thickness of 35 (Al with 7% of Mg) and with pure oxygen at a pressure of 23 cms. This lamp will yield the characteristic values indicated in column I of the table.

(The expression 50% (25%) flash-time is used to define the time which elapses between the moments when the emission of light is 50% 25%) of the maximum value in the ascending and descending branches of the characteristic curve.)

If, other things being equal, the bulb is then filled with a' mixture of 60%-by volume of Oz and 40% by volume of N20 at a pressure of 23 aim. the characteristic'values given in column II are found. If, however, the gas pressureis increased to 35 cms. and if aslightly quicker acting ignition paste is used the characteristic values of column .111 are obtained, This shows that the desired effect is completely reached by the use 4 of the invention.

The invention has the particular advantage that for obtaining a long flash-time the use of a simple filling of combustible material may suffice and in addition that even other of the abovementioned complications need not occur.

It is, however, obvious that if desired the present invention may be combined with similar means which themselves already bring about a longer flash-time so that the flash-time can be further lengthened.

The invention has the additional advantage that N20 gas is directly obtainable commercially in a sufliciently pure state. In addition, the N20 gas has no corrosive action on the usual combustible materials such as aluminium, magnesium and their alloys.

What I claim is:

1. A flash lamp comprising a transparent bulb, solid combustible material-within the bulb and adapted to react actinically with oxygen, a. mixture of oxygen and N20 within the bulb and containing from about 10% to 60% by volume of N20, and means to ignite said combustible ma- N20, and means to ignite said combustible material.

J OHANNES .ANTONIUS MARIE VAN LIEMPT. 

